Note 6 - Stockholder's Equity (Details Textual) - $ / shares
 3 Months Ended 6 Months Ended
Jun. 04, 2018
Apr. 13, 2018
Mar. 07, 2018
Jan. 12, 2018
Dec. 05, 2017
Oct. 13, 2017
Sep. 07, 2017
Jul. 13, 2017
Jun. 07, 2017
May 22, 2017
Apr. 20, 2017
Mar. 15, 2017
Aug. 18, 2015
May 13, 2013
May 06, 2013
May 31, 2018
May 31, 2017
May 31, 2018
May 31, 2017
Common Stock, Dividends, Per Share, Declared                               $ 0.01 $ 0.01 $ 0.03 $ 0.03
Preferred Stock Dividends Number of Rights Declared                             1        
Preferred Stock Dividends Number of Rights Issued                           1          
Preferred Stock Dividends Number of Rights Minimum Percent of Common Stock that must be Acquired to Make Rights Exercisable                             15.00%        
Preferred Stock Dividends Number of Rights Minimum Percent of Common Stock that Must be Acquired to Make Rights Exercisable, Institutional Investors                             20.00%        
Right to Purchase Series A Preferred Stock [Member]                                      
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right                             0.001        
Class of Warrant or Right, Exercise Price of Warrants or Rights                             $ 0.90        
Class of Warrant or Right, Term                   7 years     5 years   3 years        
Quarterly Dividend [Member]                                      
Common Stock, Dividends, Per Share, Declared     $ 0.01   $ 0.01   $ 0.01   $ 0.01     $ 0.01              
Common Stock, Dividends, Per Share, Cash Paid   $ 0.01   $ 0.01   $ 0.01   $ 0.01     $ 0.01                
Dividends Payable, Date of Record     Mar. 27, 2018                                
Quarterly Dividend [Member] | Subsequent Event [Member]                                      
Common Stock, Dividends, Per Share, Declared $ 0.01                                    
Dividends Payable, Date of Record Jun. 19, 2018                                    
Dividends Payable, Date to be Paid Jul. 06, 2018                                    
Special Cash Distribution [Member]                                      
Common Stock, Dividends, Per Share, Declared         $ 0.01                            
Common Stock, Dividends, Per Share, Cash Paid       $ 0.01